Molecular recognition is a pillar of modern biomolecular sciences because of its ubiquitous involvement in biochemical processes. Among the large variety of synthetic receptors developed to mimic natural systems and used for their capabilities of molecular recognition, molecularly imprinted organic materials are attracting an increasing interest because of their versatility and almost unlimited possibilities. Molecular imprinting is a technique for synthesizing polymers (molecularly imprinted polymers (MIPs)) using a template (e.g. polypeptides, proteins, bacteria or low molecular weight compounds) with specific binding sites, whereby monomers are polymerized in the presence of the template. The synthesized polymer then possesses molecular recognition properties for a target being complementary to the template. The MIPs adopt a structure containing recognition imprints (imprints) where binding-functions capable of chemical interactions with the target are specifically oriented by interaction with the template. When the template is washed-off, the binding-functions per imprint are conserved. The so-produced MIPs have been demonstrated to possess enhanced molecular recognition properties for the target, and thus, serve as a polymerized recognition material or element.
Molecular imprinting has been described, for example, by Wulff et al. but its development was hindered at the early stage by tedious experimental protocols (Wulff et al., Angew. Chem. Int. Ed. Engl., 1972, 11, 341). Improvement and optimizations have led to more developed and applicable systems compatible with commercial applications. Two different imprinting approaches are known in the art: the first one consists in grafting covalently a target to the polymer-forming building blocks such as monomers while the second approach is based on the non-covalent interactions of a template with monomers.
A main limitation of methods described in the art is a limited availability of binding-functions of a polymerized recognition material. Indeed, bulk-polymerization of monomers around a template causes a formation of the binding-functions inside a so-formed polymer thus limiting an application to target molecules which can diffuse inside a polymer (size and solubility limitation) and to inexpensive targets.
Different approaches have been proposed to circumvent this limitation including creating imprints only at a surface of a polymer, thus forming a polymerized recognition material. One approach is explored based on a growth of a monomolecular layer on a surface where a template is immobilized. After growth of the monomolecular layer on the surface, the template is removed from the surface and, thus, a so-formed molecular recognition element can be used for molecular recognition of a target. However, this approach is limited to small molecules because of limited thickness (i.e. in a range of 1 to 2 nm) of the monomolecular layer as polymerized recognition material of the molecular recognition element. Another approach known in the art is described by Shiomi et al. (Biomaterials 2005, 26, 5564-5571) and relates to a preparation of a molecular recognition element for a target (e.g. protein) by molecular imprinting using a covalently immobilized template on a silica surface, onto which silane polymerization was performed in order to generate a polymerized recognition material. Within this method, hemoglobin (Hb) has been employed as template protein for creating Hb-specific imprints on the silica surface. However, this method is pretty limited and not applicable to a larger supramolecular complex, e.g. virus. Moreover, it does not allow controlling of degree of affinity of the polymerized recognition material of the molecular recognition element for its target.
There is therefore an unmet need for a method providing a molecular recognition element, wherein a control and adjustment of specificity and affinity for binding targets such as small targets with low molecular weight or particularly of complex targets with high molecular weight to a polymerized recognition material of the molecular recognition element is enabled.